Question

which color indicates the presence of fe³⁺ when it reacts with thiocyanate ion (scn⁻) in an acidic solution? a blue b blood red c green d yellow

Explanation:

In an acidic solution, ferric ions ($\ce{Fe^{3+}}$) react with thiocyanate ions ($\ce{SCN^-}$) to form a complex ion (such as $\ce{[Fe(SCN)(H_2O)_5]^{2+}}$ or other similar complexes) that exhibits a blood - red color. This is a characteristic test for the presence of $\ce{Fe^{3+}}$ ions. Options A (Blue), C (Green), and D (Yellow) do not correspond to the color of the complex formed between $\ce{Fe^{3+}}$ and $\ce{SCN^-}$ in acidic solution.

Answer:

B. Blood red